The invention relates to a case base for large-caliber ammunition, in which the case jacket comprises a combustible material.
A case base of this type is known from, for example, DE 23 03 790 C3. It comprises a metallic base plate and a support ring (case stub) that projects axially beyond the base plate at its edge and is provided with a pullout edge. The support ring serves to support the base side of the case jacket, and assures a gas-tight seal when a shot is fired (case obturation), because it expands in the barrel due to the fairly high gas pressures, and rests radially against the weapon barrel. The known case base further includes a rubber obturation ring that is disposed on the projectile side of the support ring
One of the disadvantages of the known case base is that it is relatively costly to produce, because the high stresses during firing require the use of a forged steel blank, which must then be quenched and drawn in a special heat treatment, and then finished by machining. The known case base is only reusable once, because it must be machined for reuse, and the support and sealing ring could not assure the obturation in repeated use.
It is known from DE 42 29 559 A1 to construct the case base of large-caliber ammunition in two parts, namely a metallic base plate and a separate, metallic support and sealing ring. The base plate and the support and sealing ring are connected with a form fit that allows a radial decoupling of the two parts, that is, when the support and sealing ring expands radially, the sealing ring exerts no significant tensile forces on the base plate. Consequently, the base plate can be produced from a less solid material than the support and sealing ring. The initial obturation is, again, effected by means of an additional, relatively narrow elastomer ring.
One drawback of this case base is that it is likewise relatively costly to produce because of the multiple parts of base plate and case stub, and the necessity of connecting these parts to one another.
Finally, German Patent No. DE 197 29 291.7 discloses a case base in which there is no case obturation. Instead, this function is assumed by an elastomer ring that is correspondingly wide and is inexpensive to produce, the ring being exchanged from shot to shot and simultaneously performing the initial obturation.
As in the cited document DE 23 03 790 C3, in this case base, the base plate and the support ring are embodied in one piece, but the height of the support ring projecting beyond the base plate in DE 197 29 291.7 is so low that the case jacket is only guided and supported to a certain degree in the base-side region, but the base plate no longer expands notably. For this reason, it is no longer necessary to use a forged material for the base plate.
In the above-described case base, the elastomer ring is vulcanized or glued onto the base plate over a wide surface in order to transmit the necessary axial forces for removing the case base from the weapon barrel. It is fairly time-consuming to produce the connection between the base plate or support ring and the obturation ring. Moreover, the elastomer ring must be mechanically removed for the reuse of the base plate, which is an involved process.
In view of DE 197 29 291.7, it is the object of the invention to provide a case base in which the obturation ring is secured to the support ring in a simple manner, and can be removed again after the ammunition has been fired.
The above object generally is achieved according to the present invention by a case base for large-caliber ammunition having a case jacket comprising a combustible material, wherein: the case base comprises a metallic base plate and a support ring that projects axially beyond the base plate at an edge of the base plate and an obturation ring that is disposed on the projectile side of the support ring and is formed of an elastomer or thermoplastic; the base plate and the support ring are embodied in one piece; the height H1 of the support ring projecting beyond the base plate has the following relationship: 0 less than H1 less than 2D, where D represents the wall thickness of the base plate; and, on its inner surface facing the obturation ring , the support ring has a groove-shaped undercut, into which the end or the obturation ring facing the support ring extends, with at least one of a form-fit and a positive lockup. Further advantageous embodiments of the invention are disclosed.
The basic concept of the invention is that, on its inside facing the obturation ring, the support ring has a groove-shaped undercut, into which the end of the obturation ring facing the support ring extends, with a form-fit and/or positive lockup.
In the simplest case, the support ring and obturation ring can be connected to one another by a snap connection. The obturation ring, which comprises an elastomer or thermoplastic, can be produced externally and then pressed onto the support ring. To simplify this joining process, slots can be provided on the obturation ring in the snap region.
In a further embodiment of the invention, it has proven advantageous to vulcanize or inject the end of the obturation ring facing the support ring onto the support ring.
Further details and advantages of the invention ensue from the following embodiments explained in conjunction with the figures.